The invention is concerned with a carbon brush with at least one pressed-in stranded copper wire.
The stranded copper wires of such known carbon brushes are typically arranged as a plait-woven hollow stranded wire, and during their manufacture are subjected to heat treatment, namely sintering, whereby the temperature is typically from around 500.degree. C. to 720.degree. C. During this treatment, an almost complete recrystallisation of the copper takes place which results in an elastic, soft stranded copper wire. The latter properties of the stranded copper wire are desirable for their use in connection with carbon brushes in order for these to fulfil their function when installed in a motor, whereby any negative influence of the stranded copper wire on bringing the carbon brush into contact with a collector using static or dynamic spring pressure should be as small as possible.
In practise, however, the opposite requirement for stiffer stranded copper wire has arisen in part, particularly with respect to the manufacture of carbon brushes with pressed-in stranded copper wire and with the brush plates manufactured automatically from these. For the manufacture of the brush plates, the carbon brushes with pressed-in stranded copper wire are fed via an oscillating conveyor, whereby the individual carbon brushes circulate around a shaker several times. To avoid as far as possible any bending of the stranded copper wire and, as a result a failure of the brushes to be transported, or problems caused by the feed line to the carbon brush assembly area, a stiffer stranded copper wire is required.